Donogh Cairbreach O'Brien
d. 1242
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About
Donogh Cairbreach O'Brien was the son of Donal Mor, the last King of North Munster, and he ruled Thomond in the first generation after the Norman arrival, when the O'Briens ceased to be kings and became lords holding of the English crown. He founded the Franciscan friary at Ennis.
Research notes
✓ (O'Hart, Irish Pedigrees (1892), 'O'Brien (No.1) King of Thomond', gen. nos. as cited; corroborated by the Annals of the Four Masters and by the DC782/R-L226 O'Brien Y-DNA study (which independently numbers this same descent 105 Brian Boru -> 120 Turlogh Donn). Wired 23 Jul 2026.): DONOGH CAIRBREACH O'BRIEN - d. 1242; THE FIRST OF THE FAMILY TO ASSUME THE SURNAME 'O'BRIEN' AND THE TITLE 'PRINCE' (of Thomond); built the palace of Clonroad by Ennis; founded Corcomroe and Kilcooley abbeys and the Franciscan friary at Ennis. m. Sabia, dau. of Donogh O'Kennedy, Lord of Muscry Tire. Father of Connor-na-Siuddine (our line). Direct ancestor - the surname O'BRIEN fixes here.